Known electric terminals of the aforementioned type comprise a secondary retaining device for ensuring correct insertion as well as retention of the terminals inside the respective cavities.
The secondary retaining device normally comprises a movable element which snaps onto the casing, and which may either be hinged integral with the casing or consist of a separate element. In either case, snap-on connection of the movable element to the casing is only possible when the terminal is correctly inserted and retained inside the cavity by the primary retaining means which normally consist of an elastically deformable lance forming part of the casing. In the event that the terminal is not properly or fully inserted, residual deformation of the primary retaining means prevents the movable element from being assembled, thus enabling the fault to be detected.
Known connectors of the type briefly described above present several drawbacks. In the event that the terminal is not fully inserted inside the cavity, the movable element may be forced into the engaged position despite interference with the primary retaining means, e.g., by breaking or deforming the contacting parts, in which case improper insertion of the terminal may go undetected due, for example, to the terminal being so positioned as to determine a precarious electrical contact. In applications, however, in which the connector is subjected to vibration, as on a motor vehicle, it is only a question of time before the connection is cut off, with all the obvious consequences this entails.
Moreover, known secondary retaining devices provide for detecting the presence of at least one improperly inserted terminal, but not for detecting which terminal is at fault.